[sysprof] libsysprof-ui: check for NULL

[Christian Hergert <chergert src gnome org>]

commit 44e06da7ec4a35a40d2263f76bfd2875f40517b3
Author: Christian Hergert <chergert redhat com>
Date:   Fri May 10 12:26:51 2019 -0700

    libsysprof-ui: check for NULL

 src/libsysprof-ui/sysprof-profiler-menu-button.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)
---
diff --git a/src/libsysprof-ui/sysprof-profiler-menu-button.c 
b/src/libsysprof-ui/sysprof-profiler-menu-button.c
index d8bd148..26858e3 100644
--- a/src/libsysprof-ui/sysprof-profiler-menu-button.c
+++ b/src/libsysprof-ui/sysprof-profiler-menu-button.c
@@ -822,15 +822,19 @@ sysprof_profiler_menu_button_validate_spawn (SysprofProfilerMenuButton *self,
     {
       g_autoptr(GPtrArray) cooked = g_ptr_array_new ();
 
-      if (g_file_test ("/.flatpak-info", G_FILE_TEST_EXISTS))
+      if (argv != NULL)
         {
-          g_ptr_array_add (cooked, "flatpak-spawn");
-          g_ptr_array_add (cooked, "--host");
-          g_ptr_array_add (cooked, "--watch-bus");
+          if (g_file_test ("/.flatpak-info", G_FILE_TEST_EXISTS))
+            {
+              g_ptr_array_add (cooked, "flatpak-spawn");
+              g_ptr_array_add (cooked, "--host");
+              g_ptr_array_add (cooked, "--watch-bus");
+            }
+
+          for (guint i = 0; argv[i] != NULL; i++)
+            g_ptr_array_add (cooked, argv[i]);
         }
 
-      for (guint i = 0; argv[i] != NULL; i++)
-        g_ptr_array_add (cooked, argv[i]);
       g_ptr_array_add (cooked, NULL);
 
       sysprof_profiler_set_spawn_argv (priv->profiler,